PEG-gebundene Oligosaccharide als biomolekulare Erkennungsstrukturen auf Grenzflächen
Notice bibliographique
Résumé
The targeting of cells to biomaterial surfaces can be achieved by functionalization of the interface with specified biomolecular recognition structures. The aim is the production of biohybrid systems with nano- and micro-structured surfaces to control the molecular mechanism of the cell. The cell surface is very “sweet” and is surrounded by a thick layer of sugars. These sugar chains are arranged like antennas which act as recognition structures and information carriers. One important glycan structure is poly-N-acetyllactosamine (poly-LacNAc) that fulfils the major function during inter- and intracellular communication events. This sugar structure has been identified as important ligand for galectin-mediated cell adhesion to extra-cellular matrix glycoproteins (laminin, fibronectin). Therefore poly-LacNAc shall be synthesized by chemo-enzymatic methods, coupled to specialized surfaces and characterized for its usage in the biomaterial research. The first step of the synthesis strategy comprised the chemical synthesis of beta-glycosides of GlcNAc to facilitate a controlled coupling onto chemically functionalized surfaces (cooperation with Prof. Dr. Kren, ASCR, Czech Republic). The best result could be reached with the product beta-D-GlcNAc-linker-NH2-tBoc which can be easily attached to amino-reactive surfaces. In a further step the glycoside was converted as acceptor substrate by human and bacterial beta-1,4-galactosyltransferases for the production of LacNAc in a biocatalytical one-pot-reaction (cooperation with Dr. W. W. Wakarchuk, NRC, Canada). The fusion protein His6-propeptide-beta-4GalT-1 turned out to be the most productive enzyme. It showed a preference for hydrophobic substrates by quantitative conversion of 5 mM acceptor substrate in 3 h. The enzymatic synthesis of poly-LacNAc structures was accomplished by the combination of His6-propeptide-beta-4GalT-1 with beta-3GlcNAcT from Helicobacter pylori. Kinetic data and conditions for an optimal conversion of the hydrophobic substrates were determined. Even more, the produced defined poly-LacNAc structures were used as acceptor substrates for further enzymatic modifications corresponding to nature or for a specific enzymatic labelling with UDP-Gal-biotin. The functionalised LacNAc and poly-LacNAc structures could be easily purified by solid phase extraction. A deprotection step yielded the amino-terminating sugar structures which were subsequently coupled to functionalised microtiter plates. The functionalisation of amino reactive microtiter plates was a suitable small scale test system. The detection of the immobilized structures could be done with commercially available lectins or with the recombinantly expressed fungal galectin His6CGL2. Even more, an enzymatic procedure could be established to label sugar structures in a specific and more sensitive way. Finally, the binding of extracellular glycoproteins (laminin, fibronectin) to the functionalized microtiter plates could be shown. After establishing the chemical and enzymatic synthesis of the poly-LacNAc structures, their immobilization onto surfaces and their detection work should be started with biomaterial surfaces. Therefore functionalization experiments were done with PEG-star surfaces in a close cooperation with Prof. Dr. Möller (DWI, RWTH Aachen). It could be shown that it was not only possible to immobilize the glycans onto the surface but also to be build up an artificial extracellular matrix via the galectin His6CGL2 with collagen IV, fibronectin and laminin. Finally, these biofunctionalized surfaces could be used for targeted cell adhesion by poly-LacNAc- and galectin-mediated binding of collagen IV.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».